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    <TITLE>package org.opengis.filter.spatial</TITLE>
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    A <CITE>spatial operator</CITE> determines whether its geometric arguments satisfy
    the stated spatial relationship. The operator {@linkplain org.opengis.filter.Filter#evaluate evaluates}
    to {@code true} if the spatial relationship is satisfied. Otherwise the operator evaluates to {@code false}.
    The following is adapted from
    <A HREF="http://www.opengis.org/docs/02-059.pdf">Filter encoding implementation</A>:

    <P ALIGN="justify">{@linkplain org.opengis.filter.spatial.SpatialOperator Spatial operators}
    are used to test whether the value of a geometric property, potentially referenced using the name of the
    property, and a (potentially literal) geometric value satisfy the spatial relationship implied by the operator.
    For example, the {@link org.opengis.filter.spatial.Overlaps} operator evaluates whether the
    value of the specified geometric property and the specified literal geometric value spatially
    overlap.</P>

    <P ALIGN="justify">The {@link org.opengis.filter.spatial.BBOX} element is defined as a convenient
    and more compact way of encoding the very common bounding box constraint based on the {@code gml:Box}
    geometry. The {@code BBOX} operator should identify all geometries that spatially interact with the box
    in some manner.</P>

    <P ALIGN="justify">The spatial operators {@link org.opengis.filter.spatial.DWithin} and
    {@link org.opengis.filter.spatial.Beyond} test whether the value of a geometric property is
    within or beyond a specified distance of the specified literal geometric value. Distance values
    are expressed using the {@linkplain org.opengis.filter.spatial.DistanceBufferOperator#getDistance distance}
    attribute. The content of the distance attribute represents the magnitude of the distance and the
    {@linkplain org.opengis.filter.spatial.DistanceBufferOperator#getDistanceUnits units} attribute
    is used to specify the units of measure.</P>
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